Simultaneous screening of microbial energetics and CO2 respiration in soil samples from different ecosystems

The calorespirometric ratio, i.e. the ratio of heat production-to-CO2 production has been used to evaluate metabolism and microbial carbon use efficiency in soil systems. But limited sample throughput and high variability when evaluating microbial energetics and CO2 respiration separately hampered its applicability in soil science. In this study we tested if heat flows and CO2 respiration can be determined simultaneously in the same soil sample without any measurable experimental biases. Heat outputs were not significantly different when CO2 respiration was determined concurrently by means of a colorimetric method. Our method provides a simple, cheap and rapid screening of the calorespirometric ratio, and in comparison with previous studies, the reproducibility of the ratios was improved. Its non-destructive nature allows combination with the characterization of the chemical and biological composition in soil systems. Used together these methods have the potential to improve our understanding of microbial communities, their processes and activities below-ground.